Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFET) are usually designed to have multiple and wider ranges of threshold voltage Vt to serve for high speed and low standby power application. For Fin Field-Effect Transistor (FinFET), thin fin structures are configured for improving performance of devices. However, the thin fin structures also result in less sensitivity of channel dopant, and therefore the range of threshold voltage Vt is limited. To increase the threshold voltage Vt, heavily doped material is employed.